Oxidative dehydrogenation process



United States Patent 3,370,087 OXIDATIVE DEHYDROGENATION PROCESS Charles Wesley Hargis, Johnson City, and Howard Seth Young, Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Continuation-impart of application Ser. No. 550,931, May 18, 1966. This application May 3, 1967, Ser. No. 635,689 12 Claims. (Cl. 260-486) ABSTRACT OF THE DISCLOSURE The selective oxidation of the alpha, beta-carbon atoms of lower alkyl radicals having functionally unsaturated groups, in the presence of sulfides of antimony, arsenic or bismuth to produce the alpha, beta unsaturated derivatives.

This application is a continuation-in-part of our copending application Serial No. 550,931, filed May 18, 1966, as a continuation-in-part of Serial No. 152,630, filed November 15, 1961, now abandoned, which was copending with and a continuation-in-part of our application Serial No. 10,107, filed February 23, 1960, now abandoned.

This invention relates to selective oxidation of unsaturated aliphatic hydrocarbon derivatives. More particularly the invention relates to selective oxidation of an alkyl derivative having a functional group in which functional unsaturation occurs, to produce a corresponding olefinic derivative.

The principal object of the invention is to provide a method for selective oxidation of a compound consisting of a lower alkyl radical attached to a functional group in which functional unsaturation occurs, and by such oxidation to produce the corresponding alpha-beta unsaturated compound. Another object of the invention is to provide a method for reacting an aliphatic derivative with a sulfide of antimony, arsensic or bismuth to produce such alpha-beta unsaturated olefinic derivatives.

The invention provides a method for selective oxidation at the alpha and beta carbon atoms of the alkyl radical in compounds consisting of a lower alkyl radical attached to a functional group in which functional unsaturation occurs between the first carbon atom and an adjacent atom.

By functional unsaturation as the term is used in this specification we mean an unsaturated linkage, either 50 a double bond or a triple bond, between two atoms of a functional group (between the first carbon atom and an adjacent atom of the functional group in the instance of the invention). To illustrate, in the functional group of ketones 0 R(LR functional unsaturation as we use the term occurs at the double bond between C and 0.

Functional unsaturation occurs between the first carbon atom and an adjacent atom in the following functional groups for instance:

l 5 O H acld t C0 R ester 0 H!H aldehyde I? OR ketone CH=CH2 vinyl C H O H o\ /orr v CH=CH phenyl Thus, alkyl derivatives such as B CH;\ o

a I B /CH(iOH CHs-CHa-SHri-H 0 H3 1 2 and are oxidized to the corresponding alpha, beta-unsaturated derivatives and We have found that selective oxidation of the alpha, beta-carbon atoms of the alkyl radical is accomplished by action of an oxidizing agent consisting of one of, or a mixture of, the sulfides of arsenic, antimony, and bismuth. When contacted with the functionally unsaturated organic compound at elevated temperatures, the metal sulfide is reduced and yields sulfur which combines with hydrogen from the alpha and beta carbon atoms of the oxidized compound. An alpha, beta-unsaturated compound is produced.

Therefore, according to the invention, vapor of a'compound having the formula;

wherein X is a functional group in which functional unsaturation occurs between the first carbon atom and an adjacent atom, is contacted at a temperature above 100 C. with at least one member selected from the group consisting of sulfildes of arsenic, antimony, and bismuth.

In the foregoing formulae for the functionally unsaturated compounds useful in the process of our invention the substituent X is typically of the formula:

in which R when taken singly, is typically hydrogen, alkyl, hydroxy, or alkoxy. The substituents R R and R when taken singly, are hydrogen or alkyl. The substituents R and R when taken collectively, represent joined alkylene groups completing a saturated carbocyclic ring having to 6, preferably 6, carbon atoms in the ring; and the substituents R and R when taken collectively, represent joined alkylene groups completing a saturated carbocyclic ring having 5 to 6, preferably 6, carbon atoms in the ring.

The substituents R R R and R when alkyl, are typically alkyl of 1 to about 8 carbon atoms and are preferably lower alkyl, e.g., alkyl of l to about 4 carbon atoms. When R is alkoxy, it typically contains an alkyl moiety of 1 to about 8 carbon atoms. The alkyl moiety of the alkoxy group represented by R is preferably lower alkyl, e.g., alkyl of 1 to about 4 carbon atoms.

Typical of the alkyl groups represented by R R R and R are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, etc. The substituent R when alkoxy, is typically methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, etc.

When R and R collectively represent joined alkylene groups completing a carbocyclic ring, the carbocyclic rings so represented are typically cyclopentyl or cyclohexyl. When R and R collectively represent joined alkylene groups completing a carbocyclic ring, the carbocylic rings so represented are typically cyclopentyl or cyclohexyl.

The alpha,beta-unsaturated compounds formed in the process of our invention can be represented by the formula:

in which R R R and X are as defined hereinbefore, when the functionally unsaturated compound employed has only one alpha-beta position capable of being oxidatively dehydrogenated.

When the functionally unsaturated compound has two or more alpha-beta positions capable of being oxidatively dehydrogenated, dehydrogenation can occur at both positions. Thus, diethyl ketone can react with an antimony sulfide to form divinyl ketone. In a particularly interesting embodiment of this aspect of our invention, cyclohexanone reacts with an inorganic sulfide apparently to form 2 ,5-cyclohexadiene-l-one or 2,4-cyclohexadiene 1 one which immediately rearranges to phenol.

Typical of the functionally unsaturated compounds which are useful in the process of our invention are compounds such as propionaldehyde, methyl ethyl ketone, propionic acid, methyl propionate, cyclohexanone, ethylbenzene, l-butene, cyclohexanecarboxaldehyde, meth-yl cyclohexanecarboxylate, cyclohexanecarboxylic acid, cyclohexyl benzene, etc.

The process of our invention involves a reaction between the functionally unsaturated compound and the slected metal sulfide. For example, isobutyraldehyde reacts with an arsenic sulfide to form methacrolein, hydrogen sulfide, and a reduced form of the arsenic sulfide, or elemental arsenic.

The mechanics of the process consist simply of contacting the organic compound to be oxidized with a metal sulfide in a reaction zone at a temperature between 100 C. and 600 C., preferably between 150 C. and 500 C.

.4 This is conveniently done by passing a stream of vapor of the organic compound through a reaction vessel packed with particles of the selected metal sulfide. Fine particles of the metal sulfide are preferred because more surface area per unit of volume will be available for contact with the Organic vapor. In some cases it may be advantageous to dilute the vapor stream with nitrogen or other inert gas to control the temperature in the reaction zone, to reduce the rate of side-reactions, and to facilitate removal of reaction products from the reaction zone. The optimum ratio of the volume of diluent as per volume of organic vapor will depend upon the reactants being used and the reaction temperature and contact time but will usually be within the range from 0 to 2 .0 volumes inert gas per volume of organic vapor. The process is operable w thin Wide ranges of temperature, ressure and contact time. However, because of sensitivity of organic compounds to changes in temperature under oxidative conditions, consideration must be given to the relation of operating variables. For instance, the permissible range of contact time will be dilierent at various tem eratures within the preferred temperature range. With increase in tempera ture, the contact time must be decreased Commensurately to avoid excessive consumption of organic feed stock m side-reactions. The optimum contact time will be a tune tion of the organic and metal sulfide reactants chosen and of the reaction temperature but will usually fall within the range from about 0.1 to about 75 seconds. The term contact time as used in this specification is defined as the ratio of bulk contact mass volume (for instance in cubic feet) to reactant vapor feed rate (for instance in cubic feed per second). This is to be distinguished from exposure time for the metal sulfide which is the total time a sample of solid metal sulfide is exposed to reactants in the reaction zone.

To the extent found necessary, temperature in the reaction zone may be regulated by controlling feed tempera ture and, when a diluent is used, by controlling the ratio of diluent to reactant in the feed stream. The reaction proceeds at a temperature above about C. and reactions conducted at temperatures between about 325" C. and 475 C. give good product yields. Good yields are obtained at atmospheric pressure which is preferred for economic reasons, but the pressure in the reaction zone may be varied.

The sulfide or mixture of sulfides selected for a particular reaction and the valence state of the sulfide or mixture of sulfides must be considered as factors having marked influence on the choice of operating conditions. A sulfide in which the metallic element is present in a higher valence state, a valence of 5 for example, is more vigorous in oxidative action than one in a lower valence state. Less severe operating conditions such as lower reaction temperature and decreased contact time can therefore be employed when a sulfide of the higher valence state is used. Also, oxidation activity of the metal sulfides in a given valence state tends to increase as sulfides of metal 1n descending order in the periodic series are selected. For example, arsenic pentasulfide requires higher operat- 1ng temperatures and/0r more prolonged contact times for a comparable production unsaturates than does anitmony pentasulfide. The flexibility in operating conditions made possible by varying degrees of oxidation activity of the sulfides or mixtures thereof can be of considerable importance in selection of a suitable sulfide and suitable operating conditions, since the heat stability and reaction stability of the various organic compounds which may be oxidized will differ.

The following examples are given to illustrate the invention.

Example 1 5 6 plete, the temperature drops and no more 'water is tion could be oxidized to form a double bond. With comproduced. It is noted that an operable mixture of sulfides pounds in which oxidation to form a double bond can results. After flushing the reactor free of residual hydrooccur at two alpha-beta positions, both positions may be gen Sulfide with nitrogen, the sulfided mass Was contacted oxidized by the process of this invention. Some examples with 35 8- f isohlltyraldehyde d i a 'l fi 32 of such compounds are dialkylketones such as diethylminutes Gas Chromatographlc analysls of the hqmd P ketones, dialkylthioketones, dialkylvinyl compounds and duct collected in cooled receivers showed the presence of dialkyl benzenes These are oxidized by the process of methacrolem' Analysls of the gaseous efliuent Showed the the invention to the corresponding dialkenyl derivatives.

presence of hydrogen sulfide thereby demonstrating the occurrence of oxidative dehydrogenation analgous to that 10 occurring while employing the oxide form of the contact mass.

The reaction product may contain some of both the singly and the doubly oxidized derivatives.

Example 2 Example 12 A Volume of 50 Of X mesh antimony During a period of about 15 minutes, 13.8 g. of di- OXide Was Charged t0 3 l-ihch VYCOP reactor and c011" 15 isobutyl ketone is passed over a sample of a sulfide obverted to the Sulfide form y treatment Wlth hyfh'ogeh tained by treating 4X20 mesh arsenic pentoxide with Sulfide at tempferature of 460 After flushmg the hydrogen sulfide. Theinitial volume of the contact agent reactor free of residual hydrogen sulfide, the sulfided mass is about 50 The temperature is adjusted to about 0 was contacted with 15.7 g. of isobutyraldehyde during a period of 44 minutes. Examination of the reactor effluent as before showed the presence of methacrolein and hydrogen sulfide.

Using the apparatus and procedural methods of Ex- F Where 9 than one alpha'beta p051 amples 1 and 2, a number of lower aliphatic derivatives 15 avallable reactlon' ISPPhQYOHe would h may be reacted with sulfides of arsenic antimony, and pected from a Michaels reaction involving con ugate C. in the Vycor tube of Example 1. Phorone and isophorone are identified in the product. The formation of bismuth to produce the corresponding alpha-beta unsatuaddition of an activfimethylehe Component to an alpha, rated derivative. Data and results of these reactions are beta-unsaturated Compound tabulated in Table 1. In cyclohexanone and interestlng double alpha-beta TABLE I Example Sulfide Oxidizing Reaction Contact Approximate N o. AlkylDerivatives Agent From Zone Temp. Time, sec. Product Expected Conversion, percent n-Butyraldehyde 450 6-7 Crotonaldehyde. 20 Isobutyric acid-.. 450 22-24 Methacrylie acid. 10 n-Butyric acid.-- 450 22-24 Crontonic acid 8 Methyl isobutyrat 450 12-13 Methyl methacrylat 10 Propionaldehyde 475 6-7 Acrolein 5 Ethylbenzene Sb 0 505 5-6 Styrene. 20 Methyl ethyl ketone 455 10-11 Methvlymylketone 33 Diethylketone 455 11-12 Ethyl vinyl ketone 51 Butane-1 500 11-12 Butadiene 5 Alkyl derivatives having functional groups without funcoxidation occurs to form an unstable alpha-beta diene tional unsaturation may be substituted in the process and derivative that rearranges to phenol. although oxidation occurs there is a marked lack of o O OH specificity of reaction. A number of useful oxidation products are produced. lsobutyl alcohol may be oxidized to U a mixture including substantial amounts of isobutyraldeaC Ca I hyde, methacrolein, methallyl alcohol, as well as some other products. Similarly, arrays of oxidation products may be obtained from n-propyl alcohol and ethyl chloride. C

The particular solid oxidant selected for use may be E l 13 obtained in various ways such as by oxidation of the free metal or a mixture of free metals taken alone or in any desired proportions, 'by known chemical methods. Or, intermediate or lower sulfides or their mixtures may be formed by thermal decomposition and/or chemical reduction of higher sulfides or suitable mixtures thereof. Methods for aifecting these various transpositions are a matter of record and may be found by reference to the usual sources such as textbooks on inorganic chemistry. In the same manner, samples of oxidant that have lost dehydrogenating activity due to conversion to a lower sulfide or other inactive species can be regenerated by suitable chemical treatment to form the starting oxidant.

The sulfides selected for use in the process of the invention may be used in the form of solid particles of the A contact agent prepared as in Example 12 is contacted with 6.2 g. of gaseous cyclohexanone and 3000 ml. of nitrogen. From the product approximately 2 g. of phenol in addition to unreacted cyclohexanone is isolated.

Though the invention has been described with reference 60 to certain preferred embodiments, it will be understood that variations and modifications can be made within the scope of the invention as defined in the following claims.

We claim:

1. The process which comprises reacting at least one compound from the group of sulfides of arsenic, antimony, or bismuth with a functionally unsaturated compound of the formula:

sulfide or may be suspended on a carrier such as silica 2 3 gel, alumina or silica by conventional procedures. Small particles of the selected sufide can conveniently be used in a conventional circulating-fiuidized-bed reactor with in which X is a functionally unsaturated group selected the advantage that fresh sulfides may be continuously infrom those of the formula:

troduced into the reaction zone as spent solids are removed (a) O for regeneration. 1

In all of the above examples only one alpha-beta posiphorone further demonstrates the principle of extended each of R R and R when taken singly, is selected from:

(a) hydrogen or (b) alkyl;

R when taken singly, is selected from:

(a) hydrogen (b) alkyl (-c) hydroxy or (d) alkoxy;

R and R when taken collectively, represent joined alkylene groups completing a saturated carbocyclic ring having 4 to 6 carbon atoms in the ring; and R and R when taken collectively, represent joined alkylene groups completing a saturated carbocyclic ring having 4 to 6 carbon atoms in the ring.

2. The process of claim 1 in which the reaction is carried out by contacting the sulfide of arsenic, antimony, or bismuth with the functionally unsaturated compound for about 0.1 to about 75 seconds at a temperature above 100 C.

3. The process of claim 2 in which the functionally unsaturated compound is isobutyraldehyde and the products of the reaction include methacrolein and hydrogen sulfide.

4. The process of claim 2 in which the functionally unsaturated compound is n-butyraldehyde and the products of the reaction include crotonaldehyde and hydrogen sulfide.

5. The process of claim 2 in which the functionally unsaturated compound is isobutyric acid and the products of the reaction include methacrylic acid and hydrogen sulfide.

6. The process of claim 2 in which the functionally unsaturated compound is n-butyric acid and the products of the reaction include crotonic acid and hydrogen sulfide.

7. The process of claim 2 in which the functionally unsaturated compound is methyl isobutyrate and the products of the reaction include methyl methacrylate and hydrogen sulfide.

8. The process of claim 2 in which the functionally unsaturated compound is propionaldehyde and the products of the reaction include acrolein and hydrogen sulfide.

9. The process of claim 2 in which the functionally unsaturated compound is ethylbenzene and the products of the reaction include styrene and hydrogen sulfide.

10. The process of claim 2 in which the functionally unsaturated compound is cyclohexanone and the products of the reaction include phenol and hydrogen sulfide.

11. The process .of claim 2 in which the functionally unsaturated compound is methyl ethyl ketone and the products of the reaction include methyl vinyl ketone and hydrogen sulfide.

12. The process of claim 2 in which the functionally unsaturated compound is butene-l and the products of the reaction include butadiene and hydrogen sulfide.

References Cited UNITED STATES PATENTS 6/1945 Fuller et al. 260673.5 7/1960 McDaniel 260-486 UNITED STATES PATENT QFFICE CERTIFICATE OF CORRECTION Patent No. 3,370,087 February 20, 1968 Charles Wesley Hargis et a1. It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, after line 75, insert (b) -CH=CH2 Signed and sealed this 2nd day of September 1969.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Attesting Officer 

